1. Field of the Invention
This invention relates in general to offshore drilling, and in particular to equipment and methods for running tubing or casing with an offshore rig that uses a surface blowout preventer.
2. Background of the Invention
When completing a subsea well for subsea production, a riser extends from a surface vessel and attaches to the subsea well. A tubing hanger is lowered with a conduit through the riser and landed in the tubing spool and wellhead assembly. A tubing hanger running tool that is connected to the upper end of the tubing hanger sets the seal and locking member of landing of the tubing hanger. A control line extends from the running tool alongside the conduit to the surface platform. A lower marine riser package (“LMRP”) and subsea blowout preventer (“BOP”) can be utilized for safety and pressure control. In arrangements in which the BOP provides the main basis for pressure control, the BOP typically closes in on and engages the outer surface of the tubing hanger running tool.
During certain completion operations, the operator closes the BOP on the outer surface of the tubing hanger running tool. This enables the operator to apply pressure to the tubing hanger for testing purposes. Circulation operations can be performed through the subsea well with the fluid line or the conduit in the riser as either return or entry ways for the fluid. One of the drawbacks of these arrangements is that the LMRP/BOP is very large and bulky with numerous electrical and hydraulic control lines extending from the surface vessel in order to monitor and operate the subsea LMRP/BOP. The drilling riser typically has a large diameter and has a large number of lines extending alongside.
Accordingly, it has been proposed to utilize a surface (BOP) with a smaller subsea disconnect package during completion work on the subsea well. The surface BOP provides well control during the drilling and completion operations. The subsea disconnect package comprises a smaller, less complex assembly, which allows for emergency release of the rig from the well. The riser may be less complex, such as one using threaded joints.
An umbilical is attached to the tubing hanger running tool for supplying hydraulic fluid to the tool to perform various tasks. With a conventional subsea LMRP, the BOP closes on the running tool at a point below the attachment of the umbilical to the running tool. Normally, a BOP cannot seal around a conduit if the umbilical is alongside without damaging the umbilical. This prevents a surface BOP from being used for completion operations in the same manner as a subsea LMRP.